Influence of washing time on residual contamination of carcasses sprayed with lauric acid-potassium hydroxide.

Monday 21 June 2010

Interpretive Summary:
Experiments were conducted to determine if washing carcasses of broiler chickens in a solution of lauric acid (LA) and potassium hydroxide (KOH) solution for different times would influence the amount of bacteria recovered from the washed carcasses. Chicken carcasses were obtained from a local poultry processing facility and inoculated with a mixture of E. coli, Salmonella, and Campylobacter bacteria. The inoculated carcasses were then divided into 4 groups and washed for 0, 5, 15, or 30 seconds in a spray cabinet with the LA-KOH solution. The washed carcasses were rinsed for 15 seconds with water to remove excess LA-KOH, and the carcasses were then sampled to determine how many bacteria were still present. Results indicated that fewer of all types of bacteria were recovered from carcasses washed in LA-KOH for 5 s than from carcasses that were not washed. Also, fewer E. coli were recovered from carcasses washed for 15 seconds than for 5 seconds, while fewer Salmonella were recovered from carcasses washed for 30 seconds than for 5 seconds. No Campylobacter were recovered from carcasses washed for 15 or 30 seconds. These studies indicate that increasing the time that carcasses are spray washed with LA-KOH may successfully be used to decrease contamination of chicken carcasses by bacteria during poultry processing operations.

Technical Abstract:
A series of experiments were conducted to examine reductions in bacterial contamination of broiler carcasses washed for various times in a spray cabinet with a 2% lauric acid (LA)-1% potassium hydroxide (KOH) (w/v) solution. Forty eviscerated carcasses and 5 ceca were obtained from the processing line of a commercial poultry processing facility. An inoculated cecal paste was prepared by mixing 5 g of cecal contents with 0.3 mL of a bacterial suspension containing 108 cfu/ml each of antibiotic resistant strains of Escherichia coli, Salmonella Typhimirum, and Campylobacter coli. A 0.1 g portion of the inoculated cecal paste was applied to the skin of each carcass and allowed to dry for 15 min. Inoculated carcasses were then placed into 4 groups of 10 carcasses, and groups were washed with the LA-KOH solution for 0, 5, 15, or 30 s at 100 psi in a spray cabinet. Washed carcasses were rinsed for 15 s with sterile, deionized water to remove excess LA-KOH before whole carcass rinses were performed for 2 min in 200 mL of sterile phosphate buffered saline. Antibiotic resistant E. coli, Salmonella Typhimurium, and C. coli were enumerated in carcass rinsates. Results indicated that significantly fewer bacteria from all groups were recovered from carcasses washed in LA-KOH for 5 s than from unwashed carcasses. Furthermore, significantly fewer E. coli were recovered from carcasses washed for 15 s than for 5 s, while significantly fewer Salmonella Typhimurium were recovered from carcasses washed for 30 s than for 5 s. No C. coli were recovered from carcasses washed for 15 or 30 s. Findings indicate that increasing the time that carcasses are spray washed with LA-KOH can significantly decrease carcass contamination and that microbicidal surfactants may deserve consideration as potential sanitizers in poultry processing operations.